I. Field of the Invention
The present invention relates to liquid level sensors mounted through the sidewall of a liquid container rather than through the top or bottom thereof, and to the method of assembly thereof.
II. Description of Prior Art
To monitor the liquid level in a liquid container, such as an automobile coolant overflow reservoir or windshield washer tank, it has been the practice to provide a liquid level sensor mounted from the top of the container, such as from the cap thereof. Such a liquid level sensor includes a vertical post or rod-like member with a reed switch held adjacent to the top of the rod. The rod passes through the aperture of a toroidal buoyant member mounted around the rod with the toroid carrying a magnet along its top or bottom side so that as the buoyant member rises and falls with the level of liquid in the container, the magnet moves towards and away from the reed switch to open or close same depending on the level of the liquid in the container. An electric circuit connected to the reed switch turns on a light, for example, if the liquid level is unacceptable.
As vehicle manufacturers try to reduce the overall size of the vehicle, there has been a tendency to squeeze the container into locations that make it impractical to mount the liquid level sensor from the cap of the container. As a result, it has been proposed to mount the sensor through the sidewall of the container. Unfortunately, such an arrangement causes the rod to lay horizontal such that the buoyant toroid can no longer move with changes in liquid level.
Various proposals to change the construction of the sensor for side-mount applications are believed to be undesirable. In one proposal, the reed switch is positioned within the rod and the aperture through the buoyant toroid significantly enlarged into a slot so that the buoyant member may rise and fall relative the now-horizontally disposed rod. The magnet is repositioned to the side wall of the buoyant member parallel to the rod so as to open or close the reed switch as the liquid level changes.
While such a proposal now allows for side-mounting the sensor, it is not without important drawbacks, especially with respect to manufacturability and assembly. For example, with the enlarged slot, and to allow for sufficient movement between the rod and magnet, the buoyant member must be free to move outside the cylinder defined by the hole through which the sensor must fit to be mounted through the sidewall of the container. In order to mount the sensor, therefore, the buoyant member must be physically held within that cylinder which presents assembly difficulties.
Additionally, to manufacture the sensor, the buoyant member must be slid over the end of the rod and a retaining clip or the like secured to the end of the rod to prevent the buoyant member from sliding back off of the rod. The cost and time associated with such steps and the additional part is undesirable from a manufacturing perspective.
Moreover, foreign material tends to accumulate in the liquid being monitored. The foreign material has a tendency to clog the moving component(s) of some available side-mountable sensors rendering them less useful.